5 research outputs found
BTZ Solutions on Codimension-2 Braneworlds
We consider five-dimensional gravity with a Gauss-Bonnet term in the bulk and
an induced gravity term on a 2-brane of codimension-2. We show that this system
admits BTZ-like black holes on the 2-brane which are extended into the bulk
with regular horizons.Comment: 6 pages. Talk given at Recent Developments in Gravity (NEB XIII),
Thessaloniki, Greece, June 4-6, 2008
Instability of brane cosmological solutions with flux compactifications
We discuss the stability of the higher-dimensional de Sitter (dS) brane
solutions with two-dimensional internal space in the Einstein-Maxwel theory. We
show that an instability appears in the scalar-type perturbations with respect
to the dS spacetime. We derive a differential relation which has the very
similar structure to the ordinary laws of thermodynamics as an extension of the
work for the six-dimensional model [20]. In this relation, the area of dS
horizon (integrated over the two internal dimensions) exactly behaves as the
thermodynamical entropy. The dynamically unstable solutions are in the
thermodynamically unstable branch. An unstable dS compactification either
evolves toward a stable configuration or two-dimensional internal space is
decompactified. These dS brane solutions are equivalent to the accelerating
cosmological solutions in the six-dimensional Einstein-Maxwell-dilaton theory
via dimensional reduction. Thus, if the seed higher-dimensional solution is
unstable, the corresponding six-dimensional solution is also unstable. From the
effective four-dimensional point of view, a cosmological evolution from an
unstable cosmological solution in higher dimensions may be seen as a process of
the transition from the initial cosmological inflation to the current dark
energy dominated Universe.Comment: 11 pages, 3 figures, references added, to appear in CQ
Perturbations of Gauss-Bonnet Black Strings in Codimension-2 Braneworlds
We derive the Lichnerowicz equation in the presence of the Gauss-Bonnet term.
Using the modified Lichnerowicz equation we study the metric perturbations of
Gauss-Bonnet black strings in Codimension-2 Braneworlds.Comment: 26 pages, no figures, clarifying comments and one reference added, to
be published in JHE
Massive gravity with anisotropic scaling
We study a massive gravity theory which is Lorentz violating all the way from
ultraviolet to infrared energy scales. At short distances the theory breaks
diffeomorphism invariance and time and space scale differently. Dynamical
metric fields are introduced which upon linearization over a Minkowski
background correspond to Lorentz violating mass terms at large distances. We
perform a scalar perturbation analysis and we show that with an appropriate
choice of parameters the theory is healthy without ghosts, tachyons, strong
coupling problems and instabilitiesComment: 16 pages, 4 figures, change of title, discussion on the effect of
Lorentz violating mass terms is added. To appear in PRD. arXiv admin note:
text overlap with arXiv:0911.129